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Li R, Qian X, Gong C, Zhang J, Liu Y, Xu B, Humayun MS, Zhou Q. Simultaneous Assessment of the Whole Eye Biomechanics Using Ultrasonic Elastography. IEEE Trans Biomed Eng 2023; 70:1310-1317. [PMID: 36260593 PMCID: PMC10365545 DOI: 10.1109/tbme.2022.3215498] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Current elastography techniques in the field of ophthalmology usually target one specific tissue, such as the cornea or the sclera. However, the eye is an inter-related organ, and some ocular diseases can alter the biomechanical properties of multiple anatomical structures. Hence, there is a need to develop an imaging tool that can non-invasively, quantitatively, and accurately characterize dynamic changes among these biomechanical properties. METHODS A high resolution ultrasound elastography system was developed to achieve this goal. The efficacy and accuracy of the system was first validated on tissue-mimicking phantoms while mechanical testing measurements served as the gold standard. Next, an in vivo elevated intraocular pressure (IOP) model was established in rabbits to further test our system. In particular, elastography measurements were obtained at 5 IOP levels, ranging from 10 mmHg to 30 mmHg in 5 mmHg increments. Spatial-temporal maps of the multiple ocular tissues (cornea, lens, iris, optic nerve head, and peripapillary sclera) were obtained. RESULTS The spatial-temporal maps were acquired simultaneously for the ocular tissues at the 5 different IOP levels. The statistical analysis of the elastic wave speed was presented for ocular tissues. Finally, the mapping for the elastic wave speed of each ocular component was acquired at each IOP level. CONCLUSION Our elastography system can concurrently assess the biomechanical properties of multiple ocular structures and detect changes in biomechanical properties associated with changes in IOP. SIGNIFICANCE This system provides a novel tool to measure and quantify the biomechanical properties of the whole eye.
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Valmaggia P, Inglin N, Kaiser P, Scholl HPN, Maloca PM. Iris Color Matters—A Contractility Analysis With Dynamic Volume-Rendered Optical Coherence Tomography Pupillometry. Transl Vis Sci Technol 2022; 11:6. [DOI: 10.1167/tvst.11.11.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Philippe Valmaggia
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Department of Ophthalmology, University Hospital Basel, Basel, Switzerland
| | - Nadja Inglin
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
| | | | - Hendrik P. N. Scholl
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Department of Ophthalmology, University Hospital Basel, Basel, Switzerland
| | - Peter M. Maloca
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Department of Ophthalmology, University Hospital Basel, Basel, Switzerland
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
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Mills EP, Combs-Ramey K, Kwong GPS, Pang DSJ. Development of reference intervals for pupillometry in healthy dogs. Front Vet Sci 2022; 9:1020710. [PMID: 36387393 PMCID: PMC9643214 DOI: 10.3389/fvets.2022.1020710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 10/03/2022] [Indexed: 08/13/2023] Open
Abstract
BACKGROUND Pupillometry, the measurement of pupil size and reactivity to a stimulus, has various uses in both human and veterinary medicine. These reflect autonomic tone, with the potential to assess nociception and emotion. Infrared pupillometry reduces inaccuracies that may occur when the pupillary light reflex is determined subjectively by the examiner. To our knowledge, there are no published studies outlining normal reference intervals for automated pupillometry in dogs. OBJECTIVE The objective of this study was to develop de novo automated pupillometry reference intervals from 126 healthy canine eyes. METHODS The pupillary light reflex (PLR) was measured with a handheld pupillometer (NeurOptics™ PLR-200™ Pupillometer). Parameters recorded included maximum pupil diameter (MAX), minimum pupil diameter (MIN), percent constriction (CON), latency (LAT), average constriction velocity (ACV), maximum constriction velocity (MCV), average dilation velocity (ADV) and time to 75% pupil diameter recovery (T75). One measurement was obtained for each eye. RESULTS The following reference intervals were developed: MAX (6.05-11.30 mm), MIN (3.76-9.44 mm), CON (-37.89 to -9.64 %), LAT (0.11-0.30 s), ACV (-6.39 to -2.63 mm/ s), MCV (-8.45 to -3.75 mm/s), ADV (-0.21-1.77 mm/s), and T75 (0.49-3.20 s). CLINICAL SIGNIFICANCE The reference intervals developed in this study are an essential first step to facilitate future research exploring pupillometry as a pain assessment method in dogs.
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Affiliation(s)
- Erinn P. Mills
- Western Veterinary Specialist and Emergency Centre, Calgary, AB, Canada
| | | | - Grace P. S. Kwong
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Daniel S. J. Pang
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- Faculty of Veterinary Medicine, Université de Montréal, St Hyacinthe, QC, Canada
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Lin Y, Xiao Y, Wang L, Guo Y, Zhu W, Dalip B, Kamarthi S, Schreiber KL, Edwards RR, Urman RD. Experimental Exploration of Objective Human Pain Assessment Using Multimodal Sensing Signals. Front Neurosci 2022; 16:831627. [PMID: 35221908 PMCID: PMC8874020 DOI: 10.3389/fnins.2022.831627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 01/07/2022] [Indexed: 11/17/2022] Open
Abstract
Optimization of pain assessment and treatment is an active area of research in healthcare. The purpose of this research is to create an objective pain intensity estimation system based on multimodal sensing signals through experimental studies. Twenty eight healthy subjects were recruited at Northeastern University. Nine physiological modalities were utilized in this research, namely facial expressions (FE), electroencephalography (EEG), eye movement (EM), skin conductance (SC), and blood volume pulse (BVP), electromyography (EMG), respiration rate (RR), skin temperature (ST), blood pressure (BP). Statistical analysis and machine learning algorithms were deployed to analyze the physiological data. FE, EEG, SC, BVP, and BP proved to be able to detect different pain states from healthy subjects. Multi-modalities proved to be promising in detecting different levels of painful states. A decision-level multi-modal fusion also proved to be efficient and accurate in classifying painful states.
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Affiliation(s)
- Yingzi Lin
- Intelligent Human Machine Systems Laboratory, College of Engineering, Northeastern University, Boston, MA, United States
- *Correspondence: Yingzi Lin,
| | - Yan Xiao
- College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, TX, United States
| | - Li Wang
- Intelligent Human Machine Systems Laboratory, College of Engineering, Northeastern University, Boston, MA, United States
| | - Yikang Guo
- Intelligent Human Machine Systems Laboratory, College of Engineering, Northeastern University, Boston, MA, United States
| | - Wenchao Zhu
- Intelligent Human Machine Systems Laboratory, College of Engineering, Northeastern University, Boston, MA, United States
| | - Biren Dalip
- Intelligent Human Machine Systems Laboratory, College of Engineering, Northeastern University, Boston, MA, United States
| | - Sagar Kamarthi
- Intelligent Human Machine Systems Laboratory, College of Engineering, Northeastern University, Boston, MA, United States
| | - Kristin L. Schreiber
- Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard University, Boston, MA, United States
| | - Robert R. Edwards
- Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard University, Boston, MA, United States
| | - Richard D. Urman
- Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard University, Boston, MA, United States
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Meethal NSK, Mazumdar D, Morshchavka S, Robben J, van der Steen J, George R, Pel JJM. A haploscope based binocular pupillometer system to quantify the dynamics of direct and consensual Pupillary Light Reflex. Sci Rep 2021; 11:21090. [PMID: 34702842 PMCID: PMC8548319 DOI: 10.1038/s41598-021-00434-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 10/11/2021] [Indexed: 01/10/2023] Open
Abstract
This study described the development of a haploscope-based pupillometer for the parametrization of the Pupillary Light Reflex (PLR), and its feasibility in a set of 30 healthy subjects (light or dark-colored irides) and five patients diagnosed with Relative Afferent Pupillary Defect (RAPD). Our supplementary aim focused on evaluating the influence of iris colour on the PLR to decide whether a difference in PLR parameters should be anticipated when this system is used across ethnicities. All the participants underwent a customized pupillometry protocol and the generated pupil traces, captured by an eye tracker, were analyzed using exponential fits to derive PLR parameters. A Pupil Response Symmetry (PRS) coefficient was calculated to predict the presence of RAPD. The mean (SD) Initial PD during dilation (3.2 (0.5) mm) and the minimum PD during constriction (2.9 (0.4) mm) in the light iris group had a statistically significant (p < 0.001) higher magnitude compared to the dark iris group. The normal limits of the PRS coefficient ranged from - 0.20 to + 1.07 and all RAPD patients were outside the calculated normal limits. This proposed system, analysis strategies, and the tested metrics showed good short-term repeatability and the potential in detecting pupil abnormalities in neuro-ophthalmic diseases.
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Affiliation(s)
- Najiya S K Meethal
- Department of Neuroscience, Vestibular and Ocular Motor Research Group, Erasmus MC, Room EE 1453, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
- Medical and Vision Research Foundation, Chennai, India
| | - Deepmala Mazumdar
- Department of Neuroscience, Vestibular and Ocular Motor Research Group, Erasmus MC, Room EE 1453, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
- Medical and Vision Research Foundation, Chennai, India
| | | | - Jasper Robben
- Department of Neuroscience, Vestibular and Ocular Motor Research Group, Erasmus MC, Room EE 1453, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - J van der Steen
- Department of Neuroscience, Vestibular and Ocular Motor Research Group, Erasmus MC, Room EE 1453, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
- Royal Dutch Visio, Huizen, The Netherlands
| | - Ronnie George
- Medical and Vision Research Foundation, Chennai, India
| | - Johan J M Pel
- Department of Neuroscience, Vestibular and Ocular Motor Research Group, Erasmus MC, Room EE 1453, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
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Panda SK, Tan RKY, Tun TA, Buist ML, Nongpiur M, Baskaran M, Aung T, Girard MJA. Changes in Iris Stiffness and Permeability in Primary Angle Closure Glaucoma. Invest Ophthalmol Vis Sci 2021; 62:29. [PMID: 34714323 PMCID: PMC8558521 DOI: 10.1167/iovs.62.13.29] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Purpose To evaluate the biomechanical properties of the iris by evaluating iris movement during pupil constriction and to compare such properties between healthy and primary angle-closure glaucoma (PACG) subjects. Methods A total of 140 subjects were recruited for this study. In a dark room, the anterior segments of one eye per subject were scanned using anterior segment optical coherence tomography imaging during induced pupil constriction with an external white light source of 1700 lux. Using a custom segmentation code, we automatically isolated the iris segments from the AS-OCT images, which were then discretized and transformed into a three-dimensional point cloud. For each iris, a finite element (FE) mesh was constructed from the point cloud, and an inverse FE simulation was performed to match the clinically observed iris constriction in the AS-OCT images. Through this optimization process, we were able to identify the elastic modulus and permeability of each iris. Results For all 140 subjects (95 healthy and 45 PACG of Indian/Chinese ethnicity; age 60.2 ± 8.7 for PACG subjects and 57.7 ± 10.1 for healthy subjects), the simulated deformation pattern of the iris during pupil constriction matched well with OCT images. We found that the iris stiffness was higher in PACG than in healthy controls (24.5 ± 8.4 kPa vs. 17.1 ± 6.6 kPa with 40 kPa of active stress specified in the sphincter region; P < 0.001), whereas iris permeability was lower (0.41 ± 0.2 mm2/kPa s vs. 0.55 ± 0.2 mm2/kPa s; p = 0.142). Conclusions This study suggests that the biomechanical properties of the iris in PACG are different from those in healthy controls. An improved understanding of the biomechanical behavior of the iris may have implications for the understanding and management of angle-closure glaucoma.
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Affiliation(s)
- Satish K Panda
- Ophthalmic Engineering & Innovation Laboratory (OEIL), Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Royston K Y Tan
- Ophthalmic Engineering & Innovation Laboratory (OEIL), Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Tin A Tun
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Martin L Buist
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Monisha Nongpiur
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Mani Baskaran
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,Sankara Nethralaya, Chennai, India
| | - Tin Aung
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,Duke-NUS Medical School, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Michaël J A Girard
- Ophthalmic Engineering & Innovation Laboratory (OEIL), Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,Duke-NUS Medical School, Singapore.,Institute of Molecular & Clinical Ophthalmology, Basel, Switzerland
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Kaifie A, Reugels M, Kraus T, Kursawe M. The pupillary light reflex (PLR) as a marker for the ability to work or drive - a feasibility study. J Occup Med Toxicol 2021; 16:39. [PMID: 34493308 PMCID: PMC8422642 DOI: 10.1186/s12995-021-00330-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 08/30/2021] [Indexed: 11/10/2022] Open
Abstract
Background The PLR (pupillary light reflex) can be a marker for pathological medical conditions, such as neurodegenerative or mental health disorders and diseases as well as marker for physiological alterations, such as age, sex or iris color. PLR alterations have been described in people after alcohol consumption, as well. However, the effect of sleep deprivation on PLR parameters is still under debate. Methods The aim of this study was to investigate the feasibility of PLR measurements in sleep-deprived and alcohol-exposed participants. In addition, we wanted to identify PLR parameters that were altered by sleep deprivation and alcohol exposure. Results Altogether n = 50 participants have been included in this study. Differences in the PLR parameters initial diameter (dinit), latency (∆tlat), acceleration (∆ta), contraction velocity (ϑcon), quarter dilatation velocity (ϑ1/4dil), half dilatation time (∆t1/2), and the line integral (L(0.3500)) have been evaluated between baseline, sleep deprivation, as well as alcohol exposure. In a generalized linear mixed models design, we could observe statistically significant associations between the type of exposure and the PLR parameters half dilatation time and half dilatation time after the first light pulse (all p < 0.05). The participants’ latency showed a significant association in dependence of the type of exposure after the second light pulse (p < 0.05). Conclusion Our study delivers first promising results to further develop devices that may identify conditions that impair the ability to work or drive. Supplementary Information The online version contains supplementary material available at 10.1186/s12995-021-00330-2.
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Affiliation(s)
- Andrea Kaifie
- Institute for Occupational, Social, and Environmental Medicine, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.
| | - Martin Reugels
- Department of Medical Statistics, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Thomas Kraus
- Institute for Occupational, Social, and Environmental Medicine, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Michael Kursawe
- Institute for Occupational, Social, and Environmental Medicine, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
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8
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An experimental study of objective pain measurement using pupillary response based on genetic algorithm and artificial neural network. APPL INTELL 2021. [DOI: 10.1007/s10489-021-02458-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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9
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Ansari AS, Vehof J, Hammond CJ, Bremner FD, Williams KM. Evidence That Pupil Size and Reactivity Are Determined More by Your Parents Than by Your Environment. Front Neurol 2021; 12:651755. [PMID: 34012416 PMCID: PMC8127779 DOI: 10.3389/fneur.2021.651755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 03/29/2021] [Indexed: 01/19/2023] Open
Abstract
Purpose: A classic twin study to evaluate the relative contributions of genetic and environmental factors to resting pupil size and reactivity. Methods: Pupillometry was performed on 326 female twins (mean age 64 years) from the TwinsUK Adult Twin Registry, assessing resting pupil diameter in darkness and increasing levels of ambient light, alongside dynamic pupillary characteristics. Maximum-likelihood structural equation models estimated the proportion of trait variance attributable to genetic factors. Results: Mean (SD) pupil diameter in darkness was 5.29 mm (0.81), decreasing to 3.24 mm (0.57) in bright light. Pupil light reaction (PLR) had a mean (SD) amplitude of 1.38 mm (0.27) and latency of 250.34 milliseconds (28.58). Pupil size and PLR were not associated with iris colour, intraocular pressure or refractive error, but were associated with age (diameter β = -0.02, p = 0.016, constriction amplitude β = -0.01, p < 0.001, velocity β = 0.03, p < 0.001, and latency β = 0.98, p < 0.001). In darkness the resting pupil size showed a MZ intraclass correlation coefficient of 0.85, almost double that of DZ (0.44), suggesting strong additive genetic effects, with the most parsimonious model estimating a heritability of 86% [95% confidence interval (CI) 79-90%] with 14% (95% CI 10-21%) explained by unique environmental factors. PLR amplitude, latency and constriction velocity had estimated heritabilities of 69% (95% CI 54-79%), 40% (95% CI 21-56%), and 64% (95% CI 48-75%), respectively. Conclusion: Genetic effects are key determinants of resting pupil size and reactivity. Future studies to identify these genetic factors could improve our understanding of variation in pupil size and pupillary reactions in health and disease.
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Affiliation(s)
- Abdus Samad Ansari
- Section of Academic Ophthalmology, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom
| | - Jelle Vehof
- Section of Academic Ophthalmology, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom
- Department of Ophthalmology and Epidemiology, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands
| | - Christopher J. Hammond
- Section of Academic Ophthalmology, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom
| | - Fion D. Bremner
- Department of Neuro-Ophthalmology, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Katie M. Williams
- Section of Academic Ophthalmology, School of Life Course Sciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom
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Wong HK, Epps J, Chen S. A Comparison of Methods for Mitigating Within-Task Luminance Change for Eyewear-Based Cognitive Load Measurement. IEEE Trans Cogn Dev Syst 2020. [DOI: 10.1109/tcds.2018.2876348] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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11
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Investigating the association between eye colour and the Neurological Pupil index. Aust Crit Care 2020; 33:436-440. [DOI: 10.1016/j.aucc.2019.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 09/18/2019] [Accepted: 10/09/2019] [Indexed: 11/23/2022] Open
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Hashemi H, Pakzad R, Yekta A, Shokrollahzadeh F, Ostadimoghaddam H, Mahboubipour H, Khabazkhoob M. Distribution of iris color and its association with ocular diseases in a rural population of Iran. J Curr Ophthalmol 2018; 31:312-318. [PMID: 31528767 PMCID: PMC6742598 DOI: 10.1016/j.joco.2018.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 04/28/2018] [Accepted: 05/05/2018] [Indexed: 11/23/2022] Open
Abstract
Purpose To determine the distribution of iris color and its relationship with some ocular diseases in a rural population of Iran. Methods Two rural areas of the north and southwest of Iran were selected by a cross-sectional study using multi-stage cluster sampling. After selecting samples, the participants had an eye examination including measuring visual acuity, refraction, and Pentacam imaging. Then an eye examination for individuals was performed by slit-lamp. Results Out of 3851 invited people, 3314 participated in this study (participation rate, 86.05%). Dark brown [41.28%, confidence interval (CI) 95% = 31.88–50.68] and blue (0.99%, CI 95% = 0.57–1.41) were the most and the least type of iris colors among participants of this study. Compared to others, people with a dark iris have the biggest anterior chamber depth (ACD), angle and volume while central corneal thickness (CCT), keratometry and pupil were highest among people with a dark brown iris (P < 0.002). Considering the dark brown group as a base group, the chances of being afflicted to cataract among people with dark, light brown, green, and blue irises are 1.89 (CI 95% = 1.25–2.86), 1.53 (CI 95% = 1.17–2.01), 4.60 (CI 95% = 2.17–9.71), and 12.17 (CI 95% = 5.05–29.31), respectively. The chance of being afflicted to myopia among people with green irises and to hyperopia among people with blue irises were high (1.60, CI 95% = 1.08–2.36 and 3.20, CI 95% = 1.03–9.97, respectively). Conclusions Dark brown was the most prevalent iris color in rural areas of Iran. The index of cornea among people with dark and dark brown iris color is higher than other people, and people with light iris color are at a higher risk of developing eye disease such as cataract, corneal opacity, and refractive error. To determine this relationship and its usage for therapeutic and public health purposes, further studies are recommended.
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Affiliation(s)
- Hassan Hashemi
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.,Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
| | - Reza Pakzad
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
| | - Abbasali Yekta
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | | | - Hadi Ostadimoghaddam
- Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hassan Mahboubipour
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
| | - Mehdi Khabazkhoob
- Department of Medical Surgical Nursing, School of Nursing and Midwifery, ShahidBeheshti University of Medical Sciences, Tehran, Iran
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13
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Abstract
The pupillary light reflex (PLR) describes the constriction and subsequent dilation of the pupil in response to light as a result of the antagonistic actions of the iris sphincter and dilator muscles. Since these muscles are innervated by the parasympathetic and sympathetic nervous systems, respectively, different parameters of the PLR can be used as indicators for either sympathetic or parasympathetic modulation. Thus, the PLR provides an important metric of autonomic nervous system function that has been exploited for a wide range of clinical applications. Measurement of the PLR using dynamic pupillometry is now an established quantitative, non-invasive tool in assessment of traumatic head injuries. This review examines the more recent application of dynamic pupillometry as a diagnostic tool for a wide range of clinical conditions, varying from neurodegenerative disease to exposure to toxic chemicals, as well as its potential in the non-invasive diagnosis of infectious disease.
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Affiliation(s)
- Charlotte A Hall
- Research Centre for Topical Drug Delivery and Toxicology, University of Hertfordshire, Hatfield SP10 1JX, UK.
| | - Robert P Chilcott
- Research Centre for Topical Drug Delivery and Toxicology, University of Hertfordshire, Hatfield SP10 1JX, UK.
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14
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Ba-Ali S, Lund-Andersen H, Ahmadi H, Brøndsted AE. Effect of Intermittent versus Continuous Light Exposure on Pupillary Light Response, As Evaluated by Pupillometry. Front Neurol 2018; 8:746. [PMID: 29387040 PMCID: PMC5775973 DOI: 10.3389/fneur.2017.00746] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 12/26/2017] [Indexed: 12/11/2022] Open
Abstract
Objective Continuous and intermittent stimuli with green light affect the pupillary light response (PLR) differently. Since the majority of pupillometric studies use blue and red lights, we investigated the effect of continuous and intermittent stimulations on the PLR using red and blue lights. Methods Seventeen healthy subjects underwent continuous- and intermittent light stimuli, using red (643 nm) and blue light (463 nm). To avoid the influence of pupil size on the amount of light entering the eye, the procedures were repeated with the stimulus–eye in dilated condition. The maximal pupillary constriction and the early redilation phase of post-illumination pupillary response (PIPREarly) represented the mixed response of melanopsin and rod–cone photoreceptors. The late redilation phase of PIPR (PIPRLate) was the marker of melanopsin-containing retinal ganglion cells. Results Intermittent stimuli with blue light elicited significantly larger maximal contraction during dilated condition (P = 0.001), and larger sustained pupillary contraction under dilated as well as undilated condition (P < 0.001) compared to continuous light exposure. Except the PIPREarly during undilated condition, none of the PIPR metrics were significantly different between intermittent and continuous blue light stimuli. Intermittent red light stimuli elicited also a more sustained pupillary contraction regardless of mydriatic instillation (P ≤ 0.02). In addition, intermittent red light exposure resulted in a slightly larger PIPREarly under undilated condition (P = 0.02) and a slightly larger PIPRLate under dilated condition (P = 0.049). Except the PIPRLate to continuous red light stimulus, all PIPR parameters were larger when the light was presented after induction of unilateral mydriasis. Conclusion PLR parameters during and after light exposures depend on both the light stimulation mode and the entrance pupillary size.
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Affiliation(s)
- Shakoor Ba-Ali
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Henrik Lund-Andersen
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hamid Ahmadi
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Adam Elias Brøndsted
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Banaee T, Ansari-Astaneh MR, Pourreza H, Faal Hosseini F, Vatanparast M, Shoeibi N, Jami V. Utility of 1% Tropicamide in Improving the Quality of Images for Tele-Screening of Diabetic Retinopathy in Patients with Dark Irides. Ophthalmic Epidemiol 2017; 24:217-221. [PMID: 28658588 DOI: 10.1080/09286586.2016.1274039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
PURPOSE To compare the quality of fundus photographs taken before and after instillation of one drop of tropicamide. METHODS The 45º fundus photographs were taken with a non-mydriatic fundus camera in three conditions of the pupil; pre-mydriatic, 10 minutes after one drop of tropicamide, and fully dilated. Two photographs were taken in each condition; one centered on the macula and the other on the optic disc. Two vitreoretinal specialists graded the images. RESULTS A total of 1768 fundus photographs of 149 diabetic patients with dark irides were included. There were more ungradable images (38.1% and 50.3%, graders 1 and 2, respectively) in the non-mydriatic state than partially- (4.6% and 11.5%) or fully-dilated (15.4% and 10.0%) conditions (p < 0.001, both graders). Partially and fully dilated states had similar rates of ungradable images (p = 0.56 and p = 0.54, graders 1 and 2, respectively). Test-retest reliability (repeatability) was 92.5% and 74.3% for the two graders, respectively. Inter-grader agreement was moderate (Kappa = 0.50). CONCLUSION Non-mydriatic fundus photographs have a high rate of ungradable images in patients with dark irides. Instillation of only one drop of tropicamide improves the quality of fundus photographs, which is not furthered by adding more drops. This strategy can be used in tele-ophthalmology programs.
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Affiliation(s)
- Touka Banaee
- a Retina Research Center, Khatam-al-Anbia Eye Hospital , Mashhad University of Medical Science , Mashhad , Iran.,b Department of Ophthalmology, School of Medicine , Mashhad University of Medical Sciences , Mashhad , Iran
| | | | - Hamidreza Pourreza
- c Department of Computer Sciences, Department of Computer Engineering, School of Engineering , Ferdowsi University of Mashhad , Mashhad , Iran
| | - Fatemeh Faal Hosseini
- d Department of Computer Engineering, School of Engineering , Ferdowsi University of Mashhad , Mashhad , Iran
| | - Maryam Vatanparast
- d Department of Computer Engineering, School of Engineering , Ferdowsi University of Mashhad , Mashhad , Iran
| | - Nasser Shoeibi
- a Retina Research Center, Khatam-al-Anbia Eye Hospital , Mashhad University of Medical Science , Mashhad , Iran.,b Department of Ophthalmology, School of Medicine , Mashhad University of Medical Sciences , Mashhad , Iran
| | - Vajihe Jami
- d Department of Computer Engineering, School of Engineering , Ferdowsi University of Mashhad , Mashhad , Iran
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Gupta V, Bansal R, Gupta A, Bhansali A. Sensitivity and specificity of nonmydriatic digital imaging in screening diabetic retinopathy in Indian eyes. Indian J Ophthalmol 2016; 62:851-6. [PMID: 25230960 PMCID: PMC4185162 DOI: 10.4103/0301-4738.141039] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background: Nonmydriatic digital imaging (NMDI) is ideal for screening diabetic retinopathy (DR), but its use in Indian eyes has not been evaluated. Aim: The aim was to evaluate the sensitivity and specificity of NMDI as a screening tool in detecting DR in Indian eyes. Design: A prospective, nonrandomized, noncomparative, noninterventional study. Materials and Methods: A total of 500 diabetic patients visiting the endocrinology clinic (September 2008-June 2010) underwent NMDI (Zeiss Procam), followed by routine dilated fundus photography (FP; Zeiss Visupac 450+) of 345° retinal fields (1) optic disc and macula, (2) superotemporal, and (3) nasal to optic disc. Two-masked retina specialists graded the images for quality and severity of DR, and compared between NMDI and dilated FP. Statistical Analysis: SPSS Windows 17 for version. Results: Mean age was 52.97 ± 13.46 years (306 males: 194 females). The rate of ungradable images was 30.6% and 31% by the two observers. By observer 1, the sensitivity and specificity of detecting any DR was 58.8% and 69.1%, respectively, (κ = 0.608) and sight-threatening DR (STDR) was 63.1% and 68.9%, respectively, (κ = 0.641). By observer 2, the sensitivity and specificity was 57.3% and 68.3%, respectively, for any DR (κ = 0.593) and 62.8% and 68.3%, respectively, for STDR (κ = 0.637). The level of agreement between two observers was high (κ = 0.96). Conclusion: A high rate of poor quality photographs and low sensitivity limited the use of NMDI as a perfect screening system, particularly in dark iris population with diabetes as seen in Indian eyes.
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Affiliation(s)
- Vishali Gupta
- Department of Ophthalmology, Advanced Eye Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
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Wang Y, Zekveld AA, Naylor G, Ohlenforst B, Jansma EP, Lorens A, Lunner T, Kramer SE. Parasympathetic Nervous System Dysfunction, as Identified by Pupil Light Reflex, and Its Possible Connection to Hearing Impairment. PLoS One 2016; 11:e0153566. [PMID: 27089436 PMCID: PMC4835104 DOI: 10.1371/journal.pone.0153566] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 03/31/2016] [Indexed: 12/31/2022] Open
Abstract
CONTEXT Although the pupil light reflex has been widely used as a clinical diagnostic tool for autonomic nervous system dysfunction, there is no systematic review available to summarize the evidence that the pupil light reflex is a sensitive method to detect parasympathetic dysfunction. Meanwhile, the relationship between parasympathetic functioning and hearing impairment is relatively unknown. OBJECTIVES To 1) review the evidence for the pupil light reflex being a sensitive method to evaluate parasympathetic dysfunction, 2) review the evidence relating hearing impairment and parasympathetic activity and 3) seek evidence of possible connections between hearing impairment and the pupil light reflex. METHODS Literature searches were performed in five electronic databases. All selected articles were categorized into three sections: pupil light reflex and parasympathetic dysfunction, hearing impairment and parasympathetic activity, pupil light reflex and hearing impairment. RESULTS Thirty-eight articles were included in this review. Among them, 36 articles addressed the pupil light reflex and parasympathetic dysfunction. We summarized the information in these data according to different types of parasympathetic-related diseases. Most of the studies showed a difference on at least one pupil light reflex parameter between patients and healthy controls. Two articles discussed the relationship between hearing impairment and parasympathetic activity. Both studies reported a reduced parasympathetic activity in the hearing impaired groups. The searches identified no results for pupil light reflex and hearing impairment. DISCUSSION AND CONCLUSIONS As the first systematic review of the evidence, our findings suggest that the pupil light reflex is a sensitive tool to assess the presence of parasympathetic dysfunction. Maximum constriction velocity and relative constriction amplitude appear to be the most sensitive parameters. There are only two studies investigating the relationship between parasympathetic activity and hearing impairment, hence further research is needed. The pupil light reflex could be a candidate measurement tool to achieve this goal.
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Affiliation(s)
- Yang Wang
- Section Ear & Hearing, Dept. of Otolaryngology-Head and Neck Surgery and EMGO Institute for Health and Care Research, VU University medical center, Amsterdam, The Netherlands
- Eriksholm Research Centre, Oticon A/S, Snekkersten, Denmark
| | - Adriana A. Zekveld
- Section Ear & Hearing, Dept. of Otolaryngology-Head and Neck Surgery and EMGO Institute for Health and Care Research, VU University medical center, Amsterdam, The Netherlands
- Department of Behavioural Sciences and Learning, Linköping University, Linköping, Sweden
- Linnaeus Centre HEAD, The Swedish Institute for Disability Research, Linköping and Örebro Universities, Linköping, Sweden
| | - Graham Naylor
- MRC/CSO Institute of Hearing Research, Scottish Section, Glasgow, United Kingdom
| | - Barbara Ohlenforst
- Section Ear & Hearing, Dept. of Otolaryngology-Head and Neck Surgery and EMGO Institute for Health and Care Research, VU University medical center, Amsterdam, The Netherlands
- Eriksholm Research Centre, Oticon A/S, Snekkersten, Denmark
| | - Elise P. Jansma
- Medical Library, VU University Amsterdam, Amsterdam, the Netherlands
| | - Artur Lorens
- Institute of Physiology and Pathology of Hearing, Warsaw, Poland
| | - Thomas Lunner
- Eriksholm Research Centre, Oticon A/S, Snekkersten, Denmark
- Linnaeus Centre HEAD, The Swedish Institute for Disability Research, Linköping and Örebro Universities, Linköping, Sweden
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Sophia E. Kramer
- Section Ear & Hearing, Dept. of Otolaryngology-Head and Neck Surgery and EMGO Institute for Health and Care Research, VU University medical center, Amsterdam, The Netherlands
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Pupil size influences the eye-tracker signal during saccades. Vision Res 2016; 121:95-103. [PMID: 26940030 DOI: 10.1016/j.visres.2016.01.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 01/21/2016] [Accepted: 01/22/2016] [Indexed: 11/23/2022]
Abstract
While it is known that scleral search coils-measuring the rotation of the eye globe--and modern, video based eye trackers-tracking the center of the pupil and the corneal reflection (CR)--produce signals with different properties, the mechanisms behind the differences are less investigated. We measure how the size of the pupil affects the eye-tracker signal recorded during saccades with a common pupil-CR eye-tracker. Eye movements were collected from four healthy participants and one person with an aphakic eye while performing self-paced, horizontal saccades at different levels of screen luminance and hence pupil size. Results show that pupil-, and gaze-signals, but not the CR-signal, are affected by the size of the pupil; changes in saccade peak velocities in the gaze signal of more than 30% were found. It is important to be aware of this pupil size dependent change when comparing fine grained oculomotor behavior across participants and conditions.
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Fotiou D, Kaltsatou A, Tsiptsios D, Nakou M. Evaluation of the cholinergic hypothesis in Alzheimer's disease with neuropsychological methods. Aging Clin Exp Res 2015; 27:727-33. [PMID: 25749905 DOI: 10.1007/s40520-015-0321-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 01/20/2015] [Indexed: 11/29/2022]
Abstract
AIM This study aimed at evaluating the cholinergic hypothesis in Alzheimer's disease (AD) patients utilizing the pupillometry method, cognitive tests and Hamilton Depression Rating Scale (HAM-D), as well as to examine whether a correlation between cognitive tests and pupillometry exists. METHODS Forty-two patients with mean age 69.2 ± 7.0 years and documented AD volunteered to participate in this study, while 33 healthy matched subjects served as controls. All subjects underwent a pupillometric measurement and performed the Wechsler Memory Scale (WMS) and Mini Mental State Examination (MMSE). Also, HAM-D was used to assess the severity of depressive symptoms. The pupillometric parameters studied were (1) latency for the onset of constriction (T1), (2) maximum constriction velocity (VCmax), and (3) maximum constriction acceleration (ACmax). RESULTS In AD patients MMSE and WMS score were correlated with ACmax (r = -0.409, p < 0.05 and r = -0.513, p < 0.05, respectively) and VCmax (r = -0.664, p < 0.05 and r = -0.771, p < 0.05), respectively. Moreover, T1 was found to be significantly increased by 23 % (p < 0.05) in AD patients compared to healthy subjects. Conversely, the mean scores of VCmax and ACmax were significantly decreased in AD patients by 46 % (p < 0.05) and by 47 % (p < 0.05), respectively, as compared to healthy subjects. There was no significant difference between the two groups for HAM-D. Additionally, AD patients showed decreased score in WMS by 40 % (p < 0.05) and in MMSE by 28.5 % (p < 0.05) compared to healthy subjects. Of the indices that were studied VCmax and ACmax are governed mainly by the action of the Parasympathetic Nervous System. CONCLUSIONS The results of this study demonstrated that there is a correlation between cognitive tests and pupillometry in AD patients. Thus, pupillometry could be considered as a sensitive technique for the investigation of cholinergic deficits, which indirectly lead to memory and cognitive disorders in AD patients.
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Affiliation(s)
- Dimitrios Fotiou
- Neuroscience Division, Medicine School, A Neurology Clinic of AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Antonia Kaltsatou
- Neuroscience Division, Medicine School, A Neurology Clinic of AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.
- Department of Physical Education and Sport Science, University of Thessaly, Karies, 42100, Trikala, Greece.
| | - Dimitrios Tsiptsios
- Neuroscience Division, Medicine School, A Neurology Clinic of AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Maria Nakou
- Neuroscience Division, Medicine School, A Neurology Clinic of AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Mocan MC, Ustunel S, Dikmetas O, Bozkurt B, Irkec M. The effect of pharmacologic pupillary dilatation on anterior segment parameters in patients with exfoliation syndrome. JOURNAL OF OPTOMETRY 2014; 7:51-56. [PMID: 24646901 PMCID: PMC3938737 DOI: 10.1016/j.optom.2013.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 04/30/2013] [Accepted: 04/30/2013] [Indexed: 06/03/2023]
Abstract
PURPOSE The purpose of this study was to evaluate the effect of pharmacologic pupillary dilatation on anterior chamber depth (ACD) and anterior chamber angle (ACA) in eyes with exfoliation syndrome (XFS). METHODS Thirty-six eyes of 36 patients with XFS were evaluated with slit-lamp examination, Goldmann applanation tonometry and ultrasound biomicroscopy (UBM) under standard light conditions. Primary outcome parameters were defined as the change in ACD and ACA measured before and 40 min after instillation of a single drop of either 1% cyclopentolate (Group I; n=12), 2.5% phenylephrine (Group II; n=12) or 1% tropicamide (Group III; n=12). Change in intraocular pressure (IOP) during the same time interval was included as a secondary outcome measure. RESULTS The average predilatation ACD, ACA and IOP values in the study subjects were 2.54±0.40 mm, 27.9±6.3° and 14.9±3.1 mmHg, respectively. There were no significant differences in the mean age (p=0.461), the female/male ratio (p=0.232), baseline ACD (p=0.841), ACA (p=0.761) or IOP (p=0.070) within the three groups. Differences in dilation induced changes in ACD (p=0.108), ACA (p=0.636) and IOP (p=0.160) between the three groups were not statistically significant. CONCLUSION Pupillary dilatation with a single drop of 1.0% cyclopentolate, 2.5% phenylephrine or 1% tropicamide is not associated with shallowing of the anterior chamber or narrowing of the ACA in patients with XFS who present with open angles.
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Affiliation(s)
- Mehmet Cem Mocan
- Hacettepe University School of Medicine, Department of Ophthalmology, Ankara, Turkey.
| | - Saim Ustunel
- Hacettepe University School of Medicine, Department of Ophthalmology, Ankara, Turkey
| | - Ozlem Dikmetas
- Hacettepe University School of Medicine, Department of Ophthalmology, Ankara, Turkey
| | - Banu Bozkurt
- Selcuk University Faculty of Medicine, Department of Ophthalmology, Konya, Turkey
| | - Murat Irkec
- Hacettepe University School of Medicine, Department of Ophthalmology, Ankara, Turkey.
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Iris color and visual functions. Graefes Arch Clin Exp Ophthalmol 2012; 251:195-202. [DOI: 10.1007/s00417-012-2006-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 03/16/2012] [Accepted: 03/19/2012] [Indexed: 10/28/2022] Open
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The use of pupillometry in the assessment of cardiac autonomic function in elite different type trained athletes. Eur J Appl Physiol 2011; 111:2079-87. [DOI: 10.1007/s00421-011-1836-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 01/07/2011] [Indexed: 11/26/2022]
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Bradley JC, Bentley KC, Mughal AI, Bodhireddy H, Young RS, Brown SM. The Effect of Gender and Iris Color on the Dark-Adapted Pupil Diameter. J Ocul Pharmacol Ther 2010; 26:335-40. [DOI: 10.1089/jop.2010.0061] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Jay C. Bradley
- Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Karl C. Bentley
- Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Aleem I. Mughal
- Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Hari Bodhireddy
- Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Rockefeller S.L. Young
- Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas
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Abstract
PURPOSE Two combinations of dilation drops [1% tropicamide and 2.5% phenylephrine (TP) vs. 1% tropicamide and 1% cyclopentolate (TC)] were compared to determine time course and magnitude of dilation for patients with dark irides. METHODS Forty-five subjects, aged 4 to 32 years, with dark irides were enrolled. Photographs were taken before dilation and at 5, 10, 15, 20, 40, and 60 min after instillation of drops. Subjects received TP in one eye and TC in the fellow eye, with eyes randomized to the combination received. An examiner masked to drug combination and time used digital analysis to calculate pupil diameter for each photograph. TP and TC were compared to determine the time to reach both 6- and 7-mm pupil diameter and the percentage of subjects reaching these diameters. RESULTS Ninety-eight percent of pupils reached 6 mm with either combination; however, 80% reached 7 mm with TP and only 58% with TC (p = 0.0062, McNemars exact test). Time at which 50% of pupils reached 6 mm was not significantly different between drug combinations (TP 11 min vs. TC 12 min, Kaplan-Meier survival analysis). However, time at which 50% reached 7 mm was statistically and clinically significant (TP 32 min vs. TC 52 min, p = 0.0325). For subjects < or =10 years vs. >10 years, there was no significant difference in time at which 50% reached a 6- or 7-mm pupil with TP or TC; however, in every case, the younger group took longer. CONCLUSIONS A 6-mm pupil dilation may be obtained with either TP or TC; however, more subjects achieved a 7-mm pupil with TP than TC and had a faster time course to attain that size.
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Hashemi H, Yazdani K, Khabazkhoob M, Mehravaran S, Mohammad K, Fotouhi A. Distribution of photopic pupil diameter in the Tehran eye study. Curr Eye Res 2009; 34:378-85. [PMID: 19401881 DOI: 10.1080/02713680902853327] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE To determine the photopic pupil diameter and its determinants in a sample derived from a population-based survey in Tehran. METHODS In a cross-sectional study with a stratified random cluster sampling approach, 410 people age 14 years and over were selected from those residing in the first four municipality districts of Tehran after applying exclusion criteria, and 800 eyes (399 right eyes and 401 left eyes) were examined with the Orbscan II. The main outcome measure was the mean pupil diameter under photopic conditions, and possible correlations with potential determinants were evaluated through linear regression analyses. The design effect of a cluster sampling approach was observed and adjusted for. RESULTS The mean age of the participants was 40.6 +/- 16.8 years and 38.8% were male. The mean photopic pupil diameter (PPD) was 3.70 mm (range 2.30 to 5.10; 95% confidence interval (CI) 3.62 to 3.78). The mean PPD was 3.67 mm (95% CI, 3.54 to 3.81) in men and 3.72 mm (95% CI, 3.63 to 3.81) in women (p = 0.481). There was a significant reduction of 0.021 mm in PPD per year of aging (r = -0.49, p < 0.001). There was also a significant inverse correlation between PPD and spherical equivalent (r = -0.12, p = 0.034), while there was 0.66-mm increase in PPD with every 1.0-mm increase in the anterior chamber depth (ACD) (p < 0.001). Anisocoria, defined as a pupil diameter difference more than 0.4 mm between two eyes, was observed in 12.2% of the study population. CONCLUSION While the mean PPD measured with the Orbscan II was 3.70 mm in a sample derived from a population-based survey in Tehran, the scarcity of similar studies and reports concerning the pupil diameter measured with the Orbscan II makes it difficult to draw eligible comparisons. The pupil diameter has reverse correlations with age and spherical equivalent, a direct correlation with ACD, but is not correlated with gender.
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Affiliation(s)
- Hassan Hashemi
- Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
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Rho SS, Yang HS, Lew HM, Ahn JH. The Antimydriatic Effect of Brimonidine 0.15% on the Dark-adapted Pupil in Dark Brown Irides. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2008. [DOI: 10.3341/jkos.2008.49.10.1649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Seung Soo Rho
- Department of Ophthalmology, Ajou University School of Medicine, Suwon, Korea
| | - Hong Seok Yang
- Department of Ophthalmology, Ajou University School of Medicine, Suwon, Korea
| | - Ho Min Lew
- Department of Ophthalmology, Ajou University School of Medicine, Suwon, Korea
| | - Jae Hong Ahn
- Department of Ophthalmology, Ajou University School of Medicine, Suwon, Korea
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Kasthurirangan S, Glasser A. Age related changes in the characteristics of the near pupil response. Vision Res 2006; 46:1393-403. [PMID: 16112706 DOI: 10.1016/j.visres.2005.07.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Revised: 07/05/2005] [Accepted: 07/05/2005] [Indexed: 11/22/2022]
Abstract
Static and dynamic aspects of the near pupil response were studied in human subjects in the age range when accommodative amplitude steadily declines. Dynamic accommodative and pupillary responses to step stimuli were recorded in 66 subjects (ages: 14-45 years). Exponential fits to data provided amplitude, peak velocity and time constants. Accommodative amplitude decreased linearly with age (p < 0.05). Pupil constriction per diopter of accommodative response increased exponentially with age (p < 0.05). The amplitude of pupil constriction for a 2D stimulus decreased linearly with age (p < 0.05) and for a 5D stimulus did not change with age (p = 0.90). The latency of pupil constriction did not change with age (p = 0.65), while the mean peak velocity decreased linearly with age (p < 0.05). An increase in the amount of pupil constriction per diopter of accommodative response, but not per diopter of stimulus amplitude, suggests that the near effort per se does not increase with age. There is a slight reduction in the speed of near pupil response with age.
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Fliegert F, Kurth B, Göhler K. The effects of tramadol on static and dynamic pupillometry in healthy subjects--the relationship between pharmacodynamics, pharmacokinetics and CYP2D6 metaboliser status. Eur J Clin Pharmacol 2005; 61:257-66. [PMID: 15906019 DOI: 10.1007/s00228-005-0920-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2004] [Accepted: 03/03/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVES The main objective of the present study was to provide information on whether static and dynamic pupillometry can be used for pharmacodynamic profiling, particularly when investigating opioid-like drugs, such as tramadol. METHODS Healthy subjects (n = 26) participated in this randomised, double-blind, placebo-controlled, crossover Phase 1 study. Of these, 20 extensive metabolisers (EMs) with respect to polymorphic isoenzyme cytochrome P450 2D6 (CYP2D6) received up to 150 mg of tramadol-HCl and placebo. The 6 poor metabolisers (PMs) with respect to CYP2D6 received 100 mg tramadol-HCl and placebo. RESULTS In EMs, serum concentrations of the enantiomers of tramadol and of O-demethylated metabolite (M1) increased with increasing doses. Comparing the 100-mg dose between EMs and PMs, the latter exhibited higher serum concentrations of both enantiomers of tramadol. Serum concentrations of (+)-M1 remained below the lower limit of quantification, and that of (-)-M1 were lower than those in EMs. In EMs, doses from 100 mg tramadol-HCl on induced a significant (P<0.05) miosis as compared with placebo. The maximum mean differences from placebo after dosing with 50, 100 and 150 mg tramadol-HCL were -0.5, -0.8 and -1.1 mm, respectively, indicating a dose-dependent character of the changes. Dynamic pupillometry revealed significant (P<0.05) effects for the amplitude, latency and duration of reaction. The amplitude and velocity of constriction were decreased only at the highest dose; whereas, the changes of the amplitude reached statistical significance (P<0.05). Both the latency and reaction duration behaved in a dose-dependent manner. For the latency, significant changes compared with placebo (P<0.05) were found at the 150-mg dose level, while the reaction duration was already significantly (P<0.05) decreased from the 100-mg dose on. The velocity of redilatation did not respond at all. In PMs, no effect on the initial pupil diameter was found. Although the statistical analysis failed to demonstrate any significant change from placebo for the dynamic pupillometry, the effect-time profiles of EMs and PMs were comparable. For both metaboliser groups, a decrease of amplitude, velocity of constriction and reaction duration as well as an increase of latency was observed. In principle, the direction and magnitude of changes were comparable between EMs and PMs. Most important was the finding that the time course of effects was completely different between both groups of metabolisers. In EMs, effects slowly reached a maximum between 4 h and 10 h after dosing and diminished until 24 h; whereas, in PMs, both maximum effects and the return to baseline occurred much earlier, at approximately 3 h and 8 h, respectively. CONCLUSIONS The EMs and PMs of CYP2D6 treated with tramadol behaved differently in static and dynamic pupillometry. The reason for this could largely be explained with the aid of the metaboliser status and the pharmacokinetic properties of tramadol. In EMs, the pupillometric response was mainly driven by the (+)-M1, which comprises the mu action component of tramadol; whereas, in PMs, the non-mu component appears to play an important role. Thus, pupillometry was found to be useful in pharmacodynamic profiling and provides a good correlation with the pharmacokinetics.
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Affiliation(s)
- Frank Fliegert
- Department of Human Pharmacology, Research & Development, Grünenthal GmbH, 52099 Aachen, Germany.
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Kesler A, Shemesh G, Rothkoff L, Lazar M. Effect of brimonidine tartrate 0.2% ophthalmic solution on pupil size. J Cataract Refract Surg 2004; 30:1707-10. [PMID: 15313294 DOI: 10.1016/j.jcrs.2004.02.043] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2003] [Indexed: 11/24/2022]
Abstract
PURPOSE To evaluate the effect of brimonidine tartrate 0.2% ophthalmic solution on pupil size under scotopic and photopic luminance conditions in persons considering laser refractive surgery. SETTING Ophthalmic Health Center, Tel Aviv, Israel. METHODS The pupil size was measured in 36 eyes of 36 participants under scotopic and photopic conditions using the Colvard pupillometer (Oasis Medical) before and after brimonidine tartrate drops were administered. The pupil size was subsequently measured after 30 minutes and 4 and 6 hours. RESULTS No difference was found in pupil size before brimonidine tartrate instillation in eyes with light or dark irides. Before instillation, the mean photopic pupil size was 4.81 mm +/- 0.54 (SD) (range 4.0 to 6.0 mm). At 30 minutes, all pupils became miotic, with a mean size of 3.77 +/- 0.51 mm (range 3.0 to 5.0 mm) (P<.0001). After 6 hours, 27.8% of the pupils had returned to their previous size. Before brimonidine tartrate administration, the mean scotopic pupil size was 6.22 +/- 0.73 mm (range 5.0 to 8.0 mm). There was significant miosis to 4.57 +/- 0.84 mm (range 3.0 to 6.5 mm) (P<.0001) that continued for at least 6 hours. The miotic effect of brimonidine tartrate was stronger in eyes with light irides. CONCLUSIONS Brimonidine tartrate caused significant miosis, especially under scotopic conditions, most likely from its alpha-2 adrenergic effect. Under photopic luminance conditions, the miotic effect was pronounced.
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Affiliation(s)
- Anat Kesler
- Department of Ophthalmology, Tel Aviv Medical Center, 6 Weizmann Street, Tel Aviv 64239, Israel.
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Shemesh G, Kesler A, Lazar M, Rothkoff L. Pupil size in Jewish theological seminary students. Eur J Ophthalmol 2004; 14:206-10. [PMID: 15206645 DOI: 10.1177/112067210401400304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE To investigate the authors' clinical impression that pupil size among myopic Jewish theological seminary students is different from pupil size of similar secular subjects. METHODS This cross-sectional study was conducted on 28 male Jewish theological seminary students and 28 secular students or workers who were matched for age and refraction. All participants were consecutively enrolled. Scotopic and photopic pupil size was measured by means of a Colvard pupillometer. Comparisons of various parameters between the groups were performed using the two-sample t-test, Fisher exact test, a paired-sample t-test, a two-way analysis of variance, and Pearson correlation coefficients as appropriate. RESULTS The two groups were statistically matched for age, refraction, and visual acuity. The seminary students were undercorrected by an average of 2.35 diopters (D), while the secular subjects were undercorrected by only 0.65 D (p<0.01). The average pupil size was larger in the religious group under both scotopic and photopic luminance. This difference was maintained when the two groups were compared according to iris color under both conditions, reaching a level of statistical significance (p<0.0001). There was a significant difference in photopic pupil size between dark and light irises (p=0.049), but this difference was not maintained under scotopic conditions. CONCLUSIONS The average pupil size of young ultraorthodox seminary students was significantly larger than that of matched secular subjects. Whether this is the result of intensive close-up work or of apparently characteristic undercorrection of the myopia is undetermined.
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Affiliation(s)
- G Shemesh
- Ophthalmology Department, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
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Richman JE, McAndrew KG, Decker D, Mullaney SC. An evaluation of pupil size standards used by police officers for detecting drug impairment. ACTA ACUST UNITED AC 2004; 75:175-82. [PMID: 15058699 DOI: 10.1016/s1529-1839(04)70037-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND The Drug Evaluation and Classification (DEC) program was developed to detect, arrest, and convict drivers impaired by drugs other than alcohol. The DEC program is a training program designed to prepare police officers and other qualified persons to serve as Drug Recognition Experts (DREs). PURPOSE The purposes of this study were: (1) to determine normative values and ranges for pupillary responses using the specific DEC program protocols for pupil testing in nonimpaired persons, and (2) to appraise the suitability of the 3.0- mm to 6.5-mm pupil range as a potential sign of impairment under three conditions. METHODS Trained DRE officers measured pupi sizes using standardized DEC protocols. Pupil measurements were taken under three light levels: room light, near-total darkness, and direct light. The subjects were 250 volunteers, with an average age of 29.2 years (+/-6.1). All subjects were healthy, nonimpaired, and free of visual, and/or neurological problems. RESULTS For each pupil measured (N= 500), the mean (SD) for each of the three test conditions were: room light 3.86 (0.93) mm; near-total darkness 6.41(1.55) mm; and direct light 3.35 (0.72) mm. CONCLUSIONS This study determined normative values and potential ranges for pupillary responses using the specific DEC program protocols for pupil testing in non-impaired persons. When the presently approved DEC program pupil size range (3.0 to 6.5 mm) is compared with the results of this study, it appears that the DEC range for pupil size might be too sensitive. However, when determining impairment related to drug(s), the DRE reviews the results of all tests and draws a conclusion based on the totality of the evidence, not only on a variation in the pupil size.
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Affiliation(s)
- Jack E Richman
- The New England College of Optometry, Boston, Massachusetts, USA.
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Abstract
PURPOSE To investigate the relationship among horizontal corneal diameter, corneal thickness, anterior chamber depth, pupil size, and spherical equivalent and to evaluate the variation in these parameters attributable to age, sex, iris color, and refractive state of the eye. METHODS One thousand three hundred forty-one eyes of 688 consecutive patients who had a LASIK evaluation at World Eye Hospital were involved in the study. The information that was reviewed included age and sex of the patient, horizontal corneal diameter, corneal thickness, anterior chamber depth, iris color, pupil size (scotopic and photopic), and spherical equivalent. RESULTS The mean corneal thickness was 537.6 +/- 37.5 microm (range, 334-702). The mean anterior chamber depth was 3.5 +/- 0.38 mm (range, 1.99-4.75). The iris color was dark in 829 (61.8%) eyes and light in 512 (38.2%). The mean scotopic pupil size was 6.1 +/- 0.9 mm (range, 3.5-9.0) and the mean photopic pupil size was 4.0 +/- 0.7 mm (range, 2.1-7.4). The mean spherical equivalent was -3.4 +/- 3.7 D (range, -16.00-+7.50 D). Age was correlated with corneal thickness (r = 0.069, p = 0.012), spherical equivalent (r = 0.080, p = 0.003), and inversely correlated with corneal diameter (r = -0.367, p< 0.001), anterior chamber depth (r = -0.335, p< 0.001), scotopic pupil size (r = -0.309, p< 0.001), and photopic pupil size (r = -0.367, p< 0.001). Males had larger corneas (p< 0.001) and deeper anterior chambers (p< 0.001) than females. The eyes with a dark iris color had thicker corneas (p< 0.001), deeper anterior chambers (p< 0.001), and more minus spherical equivalents (p = 0.017) than the eyes with a light iris color. CONCLUSIONS There is a substantial range of dimensions of anterior structures of the human eye. These dimensions are related to each other and are influenced by age, sex, iris color, and refractive state of the eye.
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Bergamin O, Zimmerman MB, Kardon RH. Pupil light reflex in normal and diseased eyes: diagnosis of visual dysfunction using waveform partitioning. Ophthalmology 2003; 110:106-14. [PMID: 12511354 DOI: 10.1016/s0161-6420(02)01445-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
OBJECTIVE To evaluate changes in pupil size (corresponding to neuronal firing) within different time windows of the pupil light reflex in patients and normal subjects to understand which segments of the pupil waveform are best able to differentiate normal from abnormal subjects. DESIGN Comparative, observational case series. PARTICIPANTS Forty-nine normal subjects and 25 patients with known unilateral or asymmetric visual field damage were tested. METHODS A dual-channel infrared pupillograph was used to simultaneously record the right and left pupil diameters at a rate of 60 Hz. Each eye was stimulated alternately (30 degrees full-field, 200 milliseconds duration every 3 seconds) over 10 different stimulus intensities. The recorded waveform of the pupil light reflex was subdivided into six time windows based on landmarks corresponding to contraction onset, maximum contraction velocity, peak contraction, and maximum dilation velocity to assess which portion was most affected by disease. MAIN OUTCOME MEASURES The linear correlation between pupil contractions elicited by right versus left full-field stimulation at different light intensities provided diagnostic parameters (slope, intercept, and correlation coefficient R(2)) that were useful for differentiating normal subjects from patients and for categorizing disease. Sensitivity and specificity of the time windows were evaluated with receiver-operator curve analysis. RESULTS The diagnosis of asymmetric disease was greatest at time windows that included pupil contraction but not dilation. When the contraction phase was subdivided into an early phase and into a late phase, the late phase was the most diagnostic compared with the entire phase of contraction amplitude (onset to peak contraction). CONCLUSIONS By use of a range of light intensity, the change in pupil size measured between the time at which maximum contraction velocity occurs and the time to peak contraction provided the best response parameter for objective diagnosis of asymmetric disease of the anterior visual pathway. The waveform of the pupil light reflex may be an expression of the firing of retinal ganglion cells. Therefore, understanding which segment of the pupil light reflex provides maximal diagnostic power may give insight into how disease affects the pattern of neuronal firing rate.
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Affiliation(s)
- Oliver Bergamin
- Department of Ophthalmology and Visual Science, and Veterans Administration Hospital, University of Iowa, Iowa City, Iowa, USA
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Dütsch M, Hilz MJ, Rauhut U, Solomon J, Neundörfer B, Axelrod FB. Sympathetic and parasympathetic pupillary dysfunction in familial dysautonomia. J Neurol Sci 2002; 195:77-83. [PMID: 11867078 DOI: 10.1016/s0022-510x(01)00686-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Objective assessment of autonomic dysfunction in familial dysautonomia (FD) is largely based on the analysis of cardiovascular responses to challenge maneuvers such as orthostatic stress. Infrared pupillometry (IPM) provides an additional reliable method for cranial autonomic evaluation and has the advantage of requiring minimal cooperation.This study was performed to determine whether IPM contributes to the assessment of autonomic function in FD patients. In 14 FD patients and 14 healthy controls, we studied absolute and relative light reflex amplitude, pupillary constriction velocity (v(constr)), pupillary diameter, early and late pupillary re-dilatation velocity (v(dil 1), v(dil 2)) after dark adaptation. Prior to IPM, all patients had an ophthamological examination to evaluate refraction and corneal integrity. In comparison to controls, patients had a significant reduction of the parameters reflecting parasympathetic pupillary function (absolute light reflex amplitude 1.34 +/- 0.21 vs. l.86 +/- 0.14 mm, relative light reflex amplitude 22.74 +/- 7.11% vs. 30.76 +/- 3.57%, v(constr) 3.75 +/- 1.09 vs. 5.80 +/- 0.59 mm/s) and of the parameters reflecting sympathetic pupillary function (diameter 5.69 +/- 0.66 vs. 6.35 +/- 0.60 mm, v(dil 1) 1.29 +/- 0.23 vs. 1.95 +/- 0.23 mm/s, v(dil 2) 0.64 +/- 0.13 vs. 0.72 +/- 0.l2 mm/s; Mann-Whitney U-test: p<0.05). The non-invasive technique of IPM demonstrates dysfunction not only of the cranial parasympathetic, but also of the cranial sympathetic nervous system and, thus, further characterizes autonomic dysfunction in FD.
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Affiliation(s)
- M Dütsch
- Department of Neurology, New York University, New York, NY 10016, USA
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Vajdic CM, Kricker A, Giblin M, McKenzie J, Aitken J, Giles GG, Armstrong BK. Eye color and cutaneous nevi predict risk of ocular melanoma in Australia. Int J Cancer 2001; 92:906-12. [PMID: 11351315 DOI: 10.1002/ijc.1281] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Ethnicity, cutaneous nevi and eye color are generally accepted risk factors for melanoma of the eye, although case-control studies have produced conflicting results. We sought to determine the constitutional risk factors for melanomas of the choroid, ciliary body, iris and conjunctiva in Australia. A population-based case-control study was conducted, with case ascertainment from a prospective national incidence survey and randomly selected community controls. Two hundred and ninety cases aged 18-79 years and diagnosed between 1st January 1996 and 31st July 1998 were enrolled with 916 controls frequency matched by age, sex and State or Territory of residence. Risk of choroidal and ciliary body melanoma (n = 246) was increased in people with grey (OR 2.9, 95% CI 1.5-5.5), hazel (OR 2.2, 95% CI 1.4-3.7) and blue eyes (OR 1.7, 95% CI 1.0-2.7) compared with brown eyes. Risk was also increased in those with 4 or more nevi on their back, those unable to tan, and those who squinted when outdoors as a child. Risk was reduced in people born other than in Australia and New Zealand (OR 0.7, 95% CI 0.5-1.0). Non-brown eye color was a risk factor for iris melanoma (n = 25). No risk factors were identified for conjunctival melanoma (n = 19). Eye color is the strongest constitutional predictor of choroidal and ciliary body melanoma, and may indicate a protective effect of melanin density at these sites. An independent association with cutaneous nevi suggests a role for other genetic factors.
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Affiliation(s)
- C M Vajdic
- Cancer Research and Registers Division, New South Wales Cancer Council, Sydney, Australia
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